Equivocating theories

The first step I now take when I sit down to debate a subject with someone is to define the terms we will be using.  I cannot count the times in my younger years when I debated with a friend for hours only to finally discover that we actually agreed on everything and our only debate was really over how we should define some word.  I'd like to pass this long learned lesson on to Madison Murphy who recently wrote an article entitled "Evolution: theory not fact."  Murphy here argues with scientists but does not understand what they mean when they say "theory" and thus she ends up using theory in a different sense than they do.  Murphy is equivocating here, she is shifting between different definitions of the word theory.

Lets start with an example from my past of an argument where I wasted time debating a subject without realizing that the only point of contention was a difference in definition. The debate on the "purpose" of life is a great example.  When debating this point I have argued that life cannot have a purpose against friends who state things like the purpose of life is to reproduce.  The real issue in our debate was how we defined the word purpose.  I define purpose in two senses: 1) the tool sense: a purpose is the reason we build something (we build a hammer to pound nails thus the purpose of the hammer is to pound nails) or 2) the component sense: a purpose is how a component of a system helps the whole system (the purpose of the heart is to pump blood around the body).  However, my friends meant "goal" when they said "purpose."  Thus, I argued that life really doesn't have a purpose unless you can prove that life is really some sort of tool created by a God or some other higher power.  My friends, however, were trying to explain what goals people should try to achieve in life; thus they would say the purpose of life is to reproduce or find happiness.

My friends and I really just disagreed over the word purpose.  If I had originally realized my friends were talking about goals in life then I would have happily joined the debate and said what goals I think people should pursue.  However, both sides failed to understand each other because the word purpose was ambiguous.

Any time a word in an argument is ambiguous the problem of equivocation arises.  Equivocation is where we switch between two different definitions of a word.  Murphy runs into an equivocation problem with the word theory.  Murphy defines theory in her article as: "an unproven assumption."  This is a correct definition in a colloquial sense.  However, when scientists say theory they mean something else entirely.

In science a theory can be generally described as a highly supported set of ideas that explain a wide range of phenomena in our world.  That might sound a bit complicated so an easier way to understand this is that a theory is a simply an idea that accurately explains how our world works.  For example, Newtons theory of universal gravitation explains how gravity works.  By using Newtons theory of gravitation we can predict how objects will fall if we throw them into the air or even the motion of the planets.  Additionally, we can use the theory of gravity to know how strong a tall building must be to not collapse under its own weight.

The theory of evolution is a tool just like the theory of gravitation that can let us predict how the world works. A great example of the application of the theory of evolution is how scientists use the theory to predict what strains of flu will arise each year and thus make flu vaccines that target these predicted strains.

Because Murphy uses the wrong definition of theory she makes a clearly wrong statement:

"a theory is 'an unproven assumption.' Let's treat it as such. I have no problem learning about evolution if it's presented as what it is: unproven."  

Murphy equivocates over the word theory.  Her misunderstanding of the word theory leads her to wrongly believe that evolution is not supported by facts.  Murphy is trapped by her definition of theory and thus ignores the fact that evolution is strongly supported by evidence.  When her teacher says "there are so many facts proving [evolution's] truth that one would have to be ignorant not to believe it" Murphy ignores these facts and instead responds that she can "believe one theory over another."  She is of course right she can choose what she wants to believe.  However, if she cares about the truth she should try to understand these facts rather than being trapped by her definition of the word theory.